Male Sexuality

The idea that marijuana might have a negative impact on male sexuality was raised in November 1972. Two physicians from Cambridge City Hospital reported in the New England Journal of Medicine that three young men who were heavy marijuana smokers were found to be suffering from gynecomastia, or enlargement of the breasts, accompanied by a milky discharge from the nipples. According to the physicians, marijuana contains a feminizing ingredient that occasionally causes this syndrome in male users. The report attracted a good deal of attention in the media, but in the absence of other evidence, it was not taken seriously by marijuana smokers.
    In April 1974, the same journal published the findings of Robert Kolodny and his associates at the Reproductive Biology Research Foundation in St. Louis. The Kolodny study compared the testosterone levels of twenty male marijuana smokers with those of twenty nonsmoking males. Although they were still within normal limits, the levels in the marijuana smokers were lower than the levels in the nonsmokers. And the levels of those men who had smoked ten or more joints a day were lower than the levels of those who had been more moderate.
    In addition, six of the smokers had lower than normal sperm counts. The report speculated that intensive marijuana use could alter reproductive physiology through action on the central nervous system and on those glands that regulate the production of testosterone. The study produced no evidence of the development of breasts in men.
    Critics noted that the researchers did not measure the strength of the marijuana used and, more importantly, charged that the study had failed to determine the testosterone levels of the men before they had used marijuana. Nor did the researchers point out that testosterone levels are subject to dramatic fluctuations from day to day, and even from hour to hour, for no known reason.
    A third article, in the November 1974 issue of the journal, described a study by Dr. Jack Mendelson and his associates at the Alcohol and Drug Abuse Research Center of Harvard Medical School at McLean Hospital. Twenty-seven young men who smoked marijuana regularly were asked not to smoke for two weeks. They were then kept in a hospital ward without marijuana for six days and tested thoroughly. During the next three weeks, the subjects were allowed to smoke all the marijuana they wanted. They were tested daily during this time and for the five following days. In this way, Mendelson was able to establish the serum-testosterone levels of the men before, during, and after they smoked marijuana of predetermined potency. The Mendelson study, with its daily measurements, found that smoking marijuana appeared to be entirely unrelated to low testosterone levels. "High-dosage marijuana was not associated with suppression to testosterone levels," the report concluded.
    Soon afterward, Kolodny, evidently skeptical of Mendelson's conclusions, arranged for thirteen marijuana smokers to be confined to a hospital setting for three months. For two weeks before the experiment and for the first eleven days of confinement, the subjects abstained from marijuana. Then they were given several joints of predetermined potency every day. Kolodny found that the Mendelson conclusions were correct, but only up to a point. Curiously, during the fourth week of his study, Kolodny observed that testosterone levels began to fall, and they continued to drop in the weeks ahead. This led Kolodny to conclude that he had been right all along and that Mendelson had simply stopped too soon.
    Not necessarily, cautions Norman Zinberg. "One of the things we know about serum testosterone is that in humans, sexual excitement raises the levels. Locking up male animals in close confinement lowers the level." Zinberg argues that Kolodny's study would be more revealing if it had included controls, such as giving marijuana to only half the group that was locked up. Then, Zinberg quips, if there had been similar declines in both groups, one would at least have learned something about the effects of incarceration on young men.[2]